What is the function of a car tachometer?

[DiGabrielle]

The functions of a car tachometer are as follows: 1. Display engine speed: It reflects whether the engine is operating at normal speed and serves as a barometer for the engine's working condition. When the engine is idling or in neutral, the speed should be stable and within a reasonable range. When pressing the accelerator pedal in neutral, the speed should change smoothly with the steady rise and fall of the pedal. When holding the accelerator pedal steady, the tachometer needle should remain fixed at a certain speed mark. 2. Serve as a reference for manual transmission gear shifting: Selecting the appropriate gear shifting timing allows the engine to always operate within the most economical working range. The engine's torque reaches its maximum only within a certain range. Beyond this range, the torque will drop significantly, resulting in insufficient engine power, sluggish car acceleration, or even gear dragging and stalling.